Methods for making visible structures on or in transparent articles with the aid of a plurality of engraving points arranged alongside one another are known in a multiplicity of modifications from the prior art.
DE 4141869 B4 describes the treatment of surfaces of glass bodies using a laser. The introductory part of the description of WO 03/049952 A2 refers to the fact that it is known to apply trademarks or the like on the surface of transparent articles. In this case, the trademarks can be applied using a laser that produces a depression in the manner of an engraving. Furthermore, it is said to be known to accommodate further, in particular machine-readable, information in a “hidden” manner in the trademarks or the like. However, such marks engraved on the surface and having “hidden” information had the disadvantage that, particularly if further layers such as, for example, hard layers or antireflective layers having an almost identical refractive index—as is customary in the case of spectacle lenses—were applied to the surface, the marks can be registered by machine only inadequately, since the depressions could practically no longer be recognized as a result of the filling with the layer material.
WO 03/049952 A2 therefore recommends, similarly to DE 4407547 A1 introducing a trademark into a spectacle lens. According to WO 03/049952 A2, the mark is intended to be situated in a range of approximately 0.1 mm to 1 mm below the surface of the spectacle lens. The publication furthermore reveals that the trademark contains additional information for identifying the spectacle lens in the form of a multiplicity of tiny information elements that together form at least parts of the trademark. The information elements could also comprise spatially extended laser engraving dots. It is indicated that individual dots having a dot diameter of 5 to 10 micrometers could be produced without any problems. Furthermore, the document indicates that the information elements could have different color levels for coding information. These color codings should be concealed from the eye of the observer. It is not indicated how the different colors of the color coding can be produced.
A method for introducing at least one internal engraving into a flat body and an apparatus for carrying out the method are also described in EP 1138516 A2.
DE 102007004524 A1, which the invention takes as a departure point, discloses a method for producing an externally visible planar mark, which appears in a manner shimmering in different colors upon irradiation with visible light at different viewing angles, on the surface or within a transparent article, such as, for example, a spectacle lens. The colored shimmering appearance of the mark is achieved by means of a suitable choice of the spacings of a multiplicity of neighboring engraving dots and is attributable to diffraction phenomena at the diffraction grating formed by the regular arrangement of the engraving dots. The engraving dots may have been produced with the aid of a laser. One preferred variant consists in introducing the engraving dots into a coating situated on the surface. This can be, for example, an antireflection coating or an antistick coating having thicknesses of less than one micrometer.
The color impression and the brightness impression of the planar mark are not defined in a predetermined manner in the case of the method described in DE 102007004524 A1.